Add automated npm publish workflow with release-please

[Copilot]

This PR implements an automated npm publishing workflow using @googleapis/release-please to streamline the release process for oxc-walker.

Overview

The new workflow replaces the current manual release process (bumpp && pnpm publish) with a fully automated system that:

1. Automatically creates release PRs when code is pushed to main
2. Publishes to npm and creates GitHub releases when release PRs are merged

Implementation Details

Release Please Workflow (.github/workflows/release-please.yml)

• Triggers on pushes to the main branch
• Uses @googleapis/release-please-action@v4 configured for Node.js projects
• Analyzes conventional commits to determine version bumps
• Creates/updates release PRs with updated package.json and generated CHANGELOG.md

Publish Workflow (.github/workflows/publish.yml)

• Triggers when version tags (v*) are created (when release PRs are merged)
• Runs the full CI pipeline: install dependencies → build → test
• Publishes to npm with public access using pnpm publish
• Creates GitHub releases with auto-generated release notes

Benefits

• Zero-maintenance releases: No more manual version bumping or changelog updates
• Consistent versioning: Follows semantic versioning based on conventional commits
• Quality assurance: All releases are tested and built before publishing
• Full automation: From commit to npm package without manual intervention

Setup Requirements

To enable the workflow, repository administrators need to:

• Add NPM_TOKEN secret containing an npm authentication token with publish permissions

Backward Compatibility

This change is fully backward compatible:

• All existing scripts and build processes remain unchanged
• The manual pnpm run release script continues to work for emergency releases
• No changes to the package structure or build output

The workflow integrates seamlessly with the existing pnpm + TypeScript + vitest setup and maintains all current quality checks.

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